The invention relates generally to the reproduction of an original.
More particularly, the invention relates to a method and apparatus in which an original is scanned at a multiplicity of points to generate signals representing an image of the original. The individual signals are processed to enhance the image and the image is thereafter printed pointwise.
Electronic image processing such as disclosed, for example, in the European Patent No. 123 701 is being increasingly used in the reproduction of positive and negative colored originals. The original is first scanned electrooptically along rows and columns, i.e., point-by-point, to generate signals which represent an image of the original. These image signals are modified in accordance with predetermined criteria. As a rule, the image signals are digitized and then temporarily stored in a digital memory. The image signals are converted into an optical image by means of a printer containing a cathode ray tube which prints the image on paper. Printing is accomplished by successively exposing the paper to light in the three primary colors.
Both pointwise scanning of the original and printing of the image are performed via an objective and appropriate color filters. As the light used for scanning and printing passes through these glass bodies, a certain amount of scattering inevitably occurs. The objective employed for scanning focuses the light on a sensor which generates the image signals and the scattered light increases the light intensity at the sensor, in the dark areas of the image, beyond the desired light intensity. Similarly, the scattered light increases the light intensity on the photographic copy paper, in the light areas of the image, beyond that which is desired. Thus, the scattered light tends to falsify the image. The scattered light has an especially detrimental effect when illuminating portions of the image which require low light intensities because it greatly affects the brightness of the image.